How can I create application

Hi Iyata,
First of all, welcome to the OutSystems community!
If you're looking for some guidance in OutSystems platform, you've come to the right place!
Start by see the academy videos:
http://www.outsystems.com/academy/training/
If you want you can attend a presential bootcamp:
http://www.outsystems.com/academy/classroom-training/
Let us know if you need further help.
Cheers,
RG